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29
MARCH/APRIL 2018
●
TVPJOURNAL.COM
CONTINUING
EDUCATION
CLASSIFICATION OF
CARDIOVASCULAR–RENAL
DISORDERS
In 2015, an international group of 16 board-certified
veterinary experts reviewed the cardiovascular–renal
syndrome.
1
They defined cardiovascular–renal disorders
as "disease, toxin, or drug-induced structural and/or
functional damage to the kidney and/or cardiovascular
system, leading to disruption of the normal interactions
between these systems, to the ongoing detriment
of one or both." The group proposed the following
veterinary classifications: primarily cardiovascular,
primarily renal, and concurrent disease.
Primarily Cardiovascular Disease
Leading to Kidney Dysfunction
Mechanisms by which cardiovascular disease can lead to
kidney dysfunction include activation of the RAAS and
the sympathetic nervous system or glomerular injury
secondary to deposition of antigen–antibody complexes.
Examples include:
■ Systemic hypertension leading to glomerular disease
■ Cardiac shock, low cardiac output, and systemic
hypotension leading to decreased renal perfusion,
azotemia, and acute kidney injury (AKI)
■ Heartworm infection leading to glomerulonephritis
■ Caval syndrome leading to AKI
Primarily Renal Disease Leading
to Cardiovascular Dysfunction
Mechanisms by which renal disease can lead to
cardiovascular dysfunction involve fluid volume,
hemodynamic status, electrolyte disorders, and
altered clearance rates for cardiac drugs.
Examples include:
■ Kidney-mediated systemic hypertension, leading
to increased afterload, left ventricular hypertrophy,
and worsening mitral or aortic valve insufficiency
■ Volume overload, leading to congestion
or systemic hypertension
■ Hypokalemia or hyperkalemia,
leading to cardiac arrhythmias
■ Uremic hypodipsia, anorexia, or emesis,
leading to volume depletion and reduced
cardiac output and perfusion
■ Activation of the RAAS, leading to sodium
and water retention and cardiac and
vascular remodeling or congestion
■ Anemia secondary to chronic kidney disease
(CKD), leading to volume overload and
reduced cardiac tissue oxygenation
Concurrent Disease of Both Systems
This classification applies to cardiovascular
and renal disease that develop independently
or arise from a common trigger.
Examples of common triggers include:
■ Septic or neoplastic emboli leading
to renal and cardiac infarction
■ Gastric dilation and volvulus leading to
cardiac arrhythmias and azotemia
RECOGNIZING CARDIOVASCULAR
AND RENAL DISEASE
Cardiac and renal disease develop differently in dogs
and cats, thereby limiting our ability to generalize
among species. In dogs, common cardiac conditions
include: degenerative mitral valve disease and dilated
cardiomyopathy; in cats, they are hypertrophic
cardiomyopathy and systemic hypertension. In dogs,
common renal conditions include: glomerular disease,
pyelonephritis, and acute tubular injury; in cats,
they include idiopathic tubulo-interstitial disease.
2
Recognizing Cardiovascular Disease
in Dogs and Cats with Renal Disease
Cardiovascular disease is indicated by a history of a
respiratory problem, collapse, abdominal distension,
heart murmur, arrhythmia, muffled heart sounds, or
abnormal pulses. Appropriate diagnostics to assess
the cardiovascular system (eg, echocardiography,
electrocardiography, blood pressure measurement, and
thoracic radiography, with or without a heartworm test)
should be accompanied by a systemic health evaluation,
including a complete blood count, biochemical profile
(with or without thyroid testing), and urinalysis.
Dogs
Most heart disease in dogs is unmasked by clues
detected during physical examination (eg, murmur,
arrhythmia, or jugular pulses). At a minimum, if
a murmur is heard, 2-view thoracic radiography